Interfacial Behavior of Modified Nicotinic Acid as Conventional/Gemini Surfactants

Abstract

We report the synthesis and monolayer properties of conventional and gemini surfactants composed of nicotinic acid-based head groups with an emphasis on assessing how chemical structures affect the behavior of monolayers. A combination of Brewster angle microscopy and atomic force microscopy showed that pure hexadecyl nicotinate formed rippled strands in monolayers, and the gemini correspondents with either flexible or rigid organic linkers resulted in lobed-compact domains, which provides a simple method for patterning air-water and solid-air interfaces. The structural differences between conventional and gemini nicotinic acid-based surfactants could be explained by the interplay between line tension (that favors the formation of circular domains), balanced by dipole−dipole repulsion interaction between headgroups, which promotes extended domains. Miscibility and morphology studies of the modified nicotinic acid surfactants with palmitic acid demonstrated that the properties of mixed films can be controlled by the structure of the former. Excess Gibbs free energies of mixing indicated that the mixed films were less stable than the pure monolayers, and the positive deviations from ideality were the largest in the case of gemini surfactants.

Unusual Increasing Viscoelasticity of Wormlike Micelles Composed of Imidazolium Gemini Surfactants with Temperature

“…Imidazole, 1-bromododecane, 1-bromothetradecane, 1bromohexadecane, 1-bromooctadecane, 1-bromoectane, 1,2-dibromoethane, anhydrous ethanol, anhydrous ether, chloroform, sodium hydroxide, acrylonitrile, isopropanol, and acetone are all analytical grade reagents and were purchased from Shanghai Sinopharm Chemical Reagent Co., Ltd. [C n -2-C n im]Br 2 (n = 12,14,16,18,20) were synthesized and characterized according to the procedures described in the literature. 29 The product was characterized by using a 1 H NMR spectrum (Bruker ADVANCE 600 spectrometer) in CDCl 3 , elemental analysis, and an electrical conductivity meter.…”

“…29 The product was characterized by using a 1 H NMR spectrum (Bruker ADVANCE 600 spectrometer) in CDCl 3 , elemental analysis, and an electrical conductivity meter. Satisfactory 1 H NMR, elemental composition, and critical micellar concentration (cmc) were obtained for [C n -2-C n im]Br 2 (n = 12,14,16,18,20) surfactants, as given in the Supporting Information (Scheme 1).…”

“…Gemini surfactants have two hydrophilic hydrophobic tails and two headgroups connected by rigid or flexible spacers on the head group. , Compared to the conventional gemini surfactants, the imidazolium gemini surfactants have special properties and bigger rigid imidazolium headgroups, which have potential applications in many fields. , For example, they show a stronger self-aggregation performance, better solubility, and thermal stability. − They are used to regulate different types of chemical reactions . Therefore, it is of practical interest to study the surface activity of imidazolium gemini surfactants.…”

“…17,18 Compared to the conventional gemini surfactants, the imidazolium gemini surfactants have special properties and bigger rigid imidazolium headgroups, which have potential applications in many fields. 19,20 For example, they show a stronger self-aggregation performance, better solubility, and thermal stability. 21−23 They are used to regulate different types of chemical reactions.…”

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The viscoelasticity of wormlike micelles composed of ionic surfactants typically shows an exponential decrease with increasing temperature, which limits their application in relatively high-temperature (>90.0 °C) oilfields and the synthesis of functional materials as supramolecular templates at high temperatures. In this work, a series of imidazolium gemini surfactants, 1,9- 12,14,16,18,20), were synthesized. Their surface activities and aggregation behaviors in water were studied by electrical conductivity, rheology, polarization optical microscopy, smallangle X-ray scattering, ζ potential, and hydrogen nuclear magnetic resonance measurements.

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